| Objective:To modify the preparation of resin containing silver nanoparticles (AgNPs) and evaluate this novel light -cured (LC) resin synthesized by adding 8% of silver amine solution by weight, the color and the antibacterial efficiency of the uncured resin were evaluated, the size and dispersion of AgNPs in the cured polymer were assessed, respectively. The physical and mechanical properties of the cured specimens were analyzed.Methods:The proportional photoinitiator was added in a 1:1 Bis-GMA and TEGDMA resin mixture,0.08g silver 2-ethylhexanoate was dissolved in 1g 2-(tert-Butylamino)ethyl methacrylate (TBAEMA) for 40 minutes and then blended varying amount of Ag solution to the resin mixture, respectively. In order to exclude the influence of TBAEMA,3.5wt%TBAEMA was added as control 2. The color change of all the uncured resin were checked along the time.With the agar diffusion test (ADT),The inhibitor radius against Streptococcus mutans and Candida albicans were measured.The color change of the each group cured resin specimens were checked.70-nm-thick cured resin slices with varying Ag concentrations were cut by an ultramicrotome. The slices was observed by a TEM, the sizes of the silver particles were measured using Nano measurer 1.2 software.The Knoop microhardness of cured specimens was measured using a microhardness indenter under a load of 0.245N for 10s.The 0.05wt% disk was observed by a Field Emission Scanning Electron Microscope (FE-SEM), then the disk were analyzed by an Energy Dispersive Spectrometer (EDS)Statistical analysis was performed using SPSS 16 statistical software. The inhibitor radius,the sizes of AgNPs and the Knoop microhardness values of each group were analyzed through one-way ANOVA followed by comparison of means with SNK’s test.(p<0.05).Results:1.The color change of each uncured resin showed all the uncured resin turned still light yellow after 12 hours,but 24 hours later, the 0.2%,0.25%,0.3% uncured resin turned to light gray and other groups were still light yellow. After 48 hours except for the 0.05% keeping light yellow, all groups became darker in color with time, and a little dark sediment came into being in the resin.2. The ADT showed Control 1, Control 2 and 0.05% uncured resin did not show any antifungal activity against Streptococcus mutans. When the Ag salt concentration exceeds 0.1%, the inhibition radius increases (2.85mm-3.75mm) with concentration,but when the concentration was bigger than 0.15%, the antibacterial zone did not grow (p>0.05). Howerer, Control 1 and Control 2 inhibited the growth of Candida albicans mildly and the inhibition radius of both groups were nearly 0.8mm(p>0.05), The inhibition radius with 0.05% group was 2.11mm and with increasing concentrations of silver salt, the significant increase in inhibition radius was observed compared with control group.3. The color of cured disks showed the disks without silver solution were transparent, The cured Ag-contained resin disks became darker with the silver salt concentration increasing, from light yellow to brown and the resin disks at 0.03% Ag concentration were brown.4. The mechanical properties test showed the Knoop microhardness values of all the groups ranged from 23MPa to 26MPa. The values of the reisn disks whose Ag concentration was lower than 0.2% demonstrated no statistically significant differences compared with the control group (P>0.05). However, The Knoop microhardness values significantly reduced when the Ag concentration was 0.25% or more higher.5. The TEM images showed the mean sizes of AgNPs in all Ag-contained resin disks were 4.14-6.26nm,which were clearly visible and well dispersed throughout the polymer matrix. The bright particles in the 0.05% disk observed by FE-SEM were also proved to be AgNPs with the analysis of EDS.Conclusions:1. By adding a little of silver amine solution, the uncured resin can inhibit the growth of oral pathogenic bacteria2. We succeed in systhesizing less than lOnm particle size AgNPs with well dispersion in the cured resin. |
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